Leashing/Patience Bug

In this game- http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1967001189/205653398?tab=overview Caitlyn and I (on Nami) leashed for our jungler Sion at the blue side krugs. It was normal at first but after we left and he killed the small krug the large krug at some point lost its patience with him and reset (not sure but I don't think he actually did anything to cause that either) but its patience would only partially reset despite him holding the krug very close to where it spawns (clearly inside its spawning area where it doesn't lose patience normally). It kept losing patience and resetting for no apparent reason. I had to come back and help him burst it down (which was mostly possible thanks to his smite coming back up).